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Upgrade Setup
We will use the UpgradeBeacon pattern to implement three upgradable contract types: Home, Replica, and GovernanceRouter.
Each upgradable contract will have:
  • Proxy
    • the permanent address of the contract that external entities interact with
    • holds the storage of the contract
    • uses the logic specified by Implementation
    • uses delegatecall to forward contract calls from ProxyUpgradeBeaconImplementation
  • UpgradeBeacon
    • stores the (mutable) address of the Implementation
    • forwards delegatecalls to the Implementation
    • accepts new Implementation addresses from its Controller (thereby performing upgrades for all Proxies)
  • Implementation
    • specifies the logic of the contract
    • code is the same as a normal, non-upgradable contract implementation (though it should use upgrade-safe storage)
Each of the three UpgradeBeacon contracts will share a the same Controller — the contract with the power to perform upgrades.
The Controller contract will have two roles: controller and saver.
  • controller
    • is a transferrable role that should be performing upgrades in almost every case.
    • will be set to the GovernanceRouter Proxy, so that the Governance xApp ultimately controls the upgrades of the entire system. Note that this creates a circular dependency which makes upgrades of the GovernanceRouter Implementation particularly sensitive.
  • saver
    • is a transferrable(?) role that is responsible for recovering the system in a catastrophic failure case. Actions performed by the saver will be subject to a timelock enforced by the Controller contract.
    • will be set to a multisig contract where the signatories are a set of known / trusted community members. the signatories for the saver multisig be the same on every chain

Diagrams#

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Upgrade Setup Diagram 1
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Upgrade Setup Diagram 2
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